With rapid technical progress in light emitting diode (LED) technology, LEDs nowadays present many advantages over incandescent light sources including lower energy consumption, longer lifetime, smaller size, and lighter in weight. Recently, light emitting diodes are available in a wide range of colors with the most common being RED, BLUE and GREEN and are thus widely used in the backlight modules for displaying devices, such as cellular phones and LCDs. Nevertheless, heat dissipation is always the main issue restricting the improvement in LED luminous efficiency. Thus, with rising power output, it has grown increasingly necessary to shed excess heat with efficient heat transfer to maintain reliability for all LED manufacturers.
When a conventional LED is excited by the flow of current, generally the temperatures of components in the LED can be raised to above normal due to leakage current effect inside the semiconductor die of the LED and also inefficient heat transfer from the semiconductor die to the surrounding environment. Such above-normal temperature not only will cause damage to the components and speed the aging of the same as well, but also the optical properties of the LED are going to change with the temperature variation. For instance, the power output of an LED may reduce with the increasing of its temperature. In addition, as the color of light emitted from an LED, and thus its wavelength is determined by the energy gap of it semiconductor die, and since the energy gap is varying with the temperature variation of the semiconductor die, the wavelength of light emitted from the LED will change with the temperature variation.
In view of the heat dissipation problem that are common to the conventional LEDs, it is in need of an innovative LED that is able to reduce the leakage current and lower the in the LED economically and effectively.
Conventionally, as a voltage of 3V is usually the voltage required for exciting an LED, the drivers for LED excitation generally are configured with a voltage conversion circuit for dropping voltage to 3V from 110V. However, since the driver will have to be built large enough so as to accommodate the voltage conversion circuit, the application flexibility of LEDs is diminished.